In the mean time...back at the Ranch...
Hello Suppos owners,
I swapped out the .22uf VitQs for .033uf Russian K40s and replaced the the 220k ohm resistors for 1 meg as suggested. Still burning in, but the sound is just as detailed, clear and clean as before. Some obvious difference I can hear is in the midbass. It's now clearer with less coloration/distortion. Highs are also better. Highs are crystal clear with more detail. Struck cymbals sounds more like metal. I should let this setup burn in for a while longer before I think of doing the triode mod. Have a good evening.
Regards,
David
Hello Suppos owners,
I swapped out the .22uf VitQs for .033uf Russian K40s and replaced the the 220k ohm resistors for 1 meg as suggested. Still burning in, but the sound is just as detailed, clear and clean as before. Some obvious difference I can hear is in the midbass. It's now clearer with less coloration/distortion. Highs are also better. Highs are crystal clear with more detail. Struck cymbals sounds more like metal. I should let this setup burn in for a while longer before I think of doing the triode mod. Have a good evening.
Regards,
David
Hello OneyedK,
After 10 hours of listening, I can say the cap and resistor change is a definite improvement. The recreation of instruments in its own space and the overall clarity is so addicting. As I said before the low/mid bass is much cleaner than before with the 220k/.22uf combo. I'm guessing the VitQ and K40 caps, both PIO, produce similar sonic signatures, so I suppose you can say the increase bass clarity is due to the resistor change. I could continue messing with different combinations of cap and resistor values, types and cutoff points, but I'm happy and I'm done with this amp... Except maybe the triode mod. I need to let this amp cook a while longer to get the full measure of its capabilities. BTW, I do need to invest in a better soldering iron. My iron couldn't get hot enough to solder the leads onto the ground plane. Any suggestion?
I can't stop pulling out my old vinyl favorites. The only problem now is that I do not believe I can go back to my Fisher 800C receiver. The k40/1meg modded Suppo sounds so much better. I do miss the FM, but I have an old tuner I can hook up. Again, thanks Oneyedk for the education and the good sounds.
Regards,
David
That's the biggest problem of the Suppo pcb.
No soldering iron can solve that.
But investing in a powerfull soldering station is always a good idea, once you get used to it, you can work faster and cleaner.
I prefer Ersa over Weller (had the chance to try both at work), but I hear very good things about Hakko...
Stay away from the cheap versions, this is a long time investment. Amps and other things you work on wil come and go, but the trusted iron will stay.
Before you do the triode mod, you could change both cathode capacitors. I'd go for 1000 or 1500µF (25, 35 or 50Volts).
It will make an audible difference. Might be more pronounce in triode mode, but why wait
The Suppo PCB must have heavy copper on it. I have a cheap 50W temp-controlled iron with a 3.2mm (1/8") chisel tip that does 98% of the work I do. I drag out the cheap unregulated 75W iron if I need to do heavy duty stuff like to solder tag strips to a solid steel vintage chassis, or those massive binding posts that the Chinese like to solder to, instead of using a lug terminal on it...
A temperature-controlled 50W iron with a 3.2mm (1/8") chisel tip is ideal for tube amps, IMO. You can get a small tip for it for regular fine SS work on PCB's too. It's not so much the power rating of the iron, but more the heat reserve in the larger tip, and the ability of a temp-controlled iron to respond quickly with max power if/when required. Makes soldering a lot quicker and easier, which also gives better reliability from the soldered components, as they don't get heat-soaked by an iron that takes forever to get the heat into the solder joint. The best size tip to use IMO is the biggest one that you can use for the job that is not too cumbersome due to its size. The small model Hakko in my country is not something I would buy, it is cheaper in construction than my normal "cheap" iron. I can see the grinding marks in their tips...
Tubesteve, you got the idea, cheap amps for us to learn on. So if something blows up, its a good lesson rather than an expensive mistake. It is not so intimidating to learn on a cheap amp. And a cheap tube amp can still blow the pants off a run-of-the-mill SS amp any day IMO, in terms of listening enjoyment, not power.
Ian.
reminder 6P15 / EL84
...The Svetlana SV83 is a 12-watt power pentode which is well-suited for audio use, in either guitar amps or in high-fidelity equipment. Its original design, intended for high-accuracy video amplification, gives the SV83 high transconductance and very high linearity. The SV83 may be used in any EL84 or 6BQ5 circuit, provided that some changes are made as described below, in items 1 thru 4.
1. There is a small difference in the pinout of the SV83 versus the EL84. SV83s may not have their suppressor grid connected to the cathode internally. To insure the usability of all SV83s in an EL84 socket, do the following:
a) Insure that pins 1 and 6 of each SV83 socket are NOT connected to any circuitry, nor used as a tie point for components.
b) On each SV83 socket, connect pin 6 to pin 3, using a short wire jumper. Be sure the wire does not touch any other circuitry.
(Note: there is an issue with the pinout of SOME EL84s versus the SV83.)
2. The SV83's screen grid (pin 9) is not able to accept an operating voltage of more than 200v DC. Because nearly all EL84 amps operate their screen grids at or near the plate voltage (in pentode, ultralinear or triode connection), the amplifier must be modified to provide a lower voltage to the SV83 screen grids. If triode connection is desired, the plate supply voltage must be limited to 200v DC. For higher plate voltages, any of the following circuits will work:
a) Figure 1 is probably the lowest-cost method of deriving a screen voltage. This works adequately for most guitar amps and some vintage hi-fi amps. The screen voltage can "sag" when full power is reached, although this may not be an issue, especially in a guitar amp. A major advantage of this scheme is that the resistive divider also acts to discharge the power-supply filter capacitors when power is turned off. This circuit may be used with a single SV83 or one pair of SV83s. It adds about 15-20 mA of current drain to the plate supply, which must be allowed for in the power transformer.
b) Figure 2 is the best solution for high-end audio design. The zener diodes are a low-cost option which offer good regulation and good stability. The types shown are rated for 1 watt dissipation and are operated conservatively here. A filter capacitor may be paralleled across them to assist regulation if desired. Using the 0A2 gas regulator tube is a possible all-tube technique to achieve the same result. Although 0A2s are out of production, they are long-lasting and readily available in bulk quantities as NOS. Gas tubes can NOT be used with a parallel capacitor larger than 0.1 uF, as zeners can. The choice of which regulation method to use is up to the designer. This circuit may be used with any number of SV83s up to a quad.
3. Bias adjustment may be necessary to obtain the same plate current with SV83s as with EL84s. Typically the SV83 will require about 1-5v less negative grid voltage than EL84s for the same idle point, due to the higher transconductance and sensitivity of the SV83. If cathode bias is used in the amp, the cathode resistor may be decreased in value about 20%. The designer is urged to equip the amplifier with SV83 and try it without bias adjustments, as the resulting bias value may be acceptable. No modifications to driver circuits are required.
4. An amp which is modified to accept SV83s can be made back-compatible with EL84 types. First, a switch must be provided to DISCONNECT pin 6 from pin 3. (This is necessary because SOME EL84 and 7189 types have internal connections to pins 1 and/or 6. Many EL84s do not. This can cause some confusion.) Second, the idling plate current of the EL84 will be lower in the SV83-modified circuit. The switch above may use a second pole, whcih can be equipped to switch in different cathode-bias resistors. The switch can then be set to allow proper operation with SV83s or EL84s.
...The Svetlana SV83 is a 12-watt power pentode which is well-suited for audio use, in either guitar amps or in high-fidelity equipment. Its original design, intended for high-accuracy video amplification, gives the SV83 high transconductance and very high linearity. The SV83 may be used in any EL84 or 6BQ5 circuit, provided that some changes are made as described below, in items 1 thru 4.
1. There is a small difference in the pinout of the SV83 versus the EL84. SV83s may not have their suppressor grid connected to the cathode internally. To insure the usability of all SV83s in an EL84 socket, do the following:
a) Insure that pins 1 and 6 of each SV83 socket are NOT connected to any circuitry, nor used as a tie point for components.
b) On each SV83 socket, connect pin 6 to pin 3, using a short wire jumper. Be sure the wire does not touch any other circuitry.
(Note: there is an issue with the pinout of SOME EL84s versus the SV83.)
2. The SV83's screen grid (pin 9) is not able to accept an operating voltage of more than 200v DC. Because nearly all EL84 amps operate their screen grids at or near the plate voltage (in pentode, ultralinear or triode connection), the amplifier must be modified to provide a lower voltage to the SV83 screen grids. If triode connection is desired, the plate supply voltage must be limited to 200v DC. For higher plate voltages, any of the following circuits will work:
a) Figure 1 is probably the lowest-cost method of deriving a screen voltage. This works adequately for most guitar amps and some vintage hi-fi amps. The screen voltage can "sag" when full power is reached, although this may not be an issue, especially in a guitar amp. A major advantage of this scheme is that the resistive divider also acts to discharge the power-supply filter capacitors when power is turned off. This circuit may be used with a single SV83 or one pair of SV83s. It adds about 15-20 mA of current drain to the plate supply, which must be allowed for in the power transformer.
b) Figure 2 is the best solution for high-end audio design. The zener diodes are a low-cost option which offer good regulation and good stability. The types shown are rated for 1 watt dissipation and are operated conservatively here. A filter capacitor may be paralleled across them to assist regulation if desired. Using the 0A2 gas regulator tube is a possible all-tube technique to achieve the same result. Although 0A2s are out of production, they are long-lasting and readily available in bulk quantities as NOS. Gas tubes can NOT be used with a parallel capacitor larger than 0.1 uF, as zeners can. The choice of which regulation method to use is up to the designer. This circuit may be used with any number of SV83s up to a quad.
3. Bias adjustment may be necessary to obtain the same plate current with SV83s as with EL84s. Typically the SV83 will require about 1-5v less negative grid voltage than EL84s for the same idle point, due to the higher transconductance and sensitivity of the SV83. If cathode bias is used in the amp, the cathode resistor may be decreased in value about 20%. The designer is urged to equip the amplifier with SV83 and try it without bias adjustments, as the resulting bias value may be acceptable. No modifications to driver circuits are required.
4. An amp which is modified to accept SV83s can be made back-compatible with EL84 types. First, a switch must be provided to DISCONNECT pin 6 from pin 3. (This is necessary because SOME EL84 and 7189 types have internal connections to pins 1 and/or 6. Many EL84s do not. This can cause some confusion.) Second, the idling plate current of the EL84 will be lower in the SV83-modified circuit. The switch above may use a second pole, whcih can be equipped to switch in different cathode-bias resistors. The switch can then be set to allow proper operation with SV83s or EL84s.
Wow, I overlooked the 200V limit of g2.
This means that the Suppo Golden Voice, supplied with Chinese 6P15 tubes is actually wired in "self destruct" mode. (original schematic)
Lucky for Joe we all voided warranty
None of the mods presented before, took care of this problem
Only peepz with JJ EL84's are safe.
Do you know if Reflektor 6P15P-EV have the same limitations?
And what about 6P14P-EV.
I'm asking because I have no experience with these types, but they seem available at a nice price.
btw, you forgot to include the images.
This means that the Suppo Golden Voice, supplied with Chinese 6P15 tubes is actually wired in "self destruct" mode. (original schematic)
Lucky for Joe we all voided warranty None of the mods presented before, took care of this problem
Only peepz with JJ EL84's are safe.
Do you know if Reflektor 6P15P-EV have the same limitations?
And what about 6P14P-EV.
I'm asking because I have no experience with these types, but they seem available at a nice price.
btw, you forgot to include the images.
Last edited:
6p15
the saratov should be the same, bcc. the russians transferred technology to chinese, and construction is the same. I opened the 6P15 and took the ratios between grind number windings and distances from g1, g2 g3.
the max. given dissipation of G2 is given for 1.5W, ( 6P15). this may have a reason: first for lifetime, second for linearity. the grid wire diameters (6P15) are the same as for EL84 ( 2.5W for G2). normally, russian tubes can be overloaded to a certain degree.
The best operation, and most linear way for the 6P15 is below 200V for the G2
The 6P14 plate is rated for 14W
the 6P15 plate is rated for 12 W
but: both have the same plate dimension, i have measured.
There may be some relabeled for a reason. dont know. in europe, a failed EL84 were relabeled as EL82 with less rating.
as i am incontact with suppo, we will test an check these things , and inform the community about the results.
my general advice: stay with the 6P15 instead of EL84, bcc. its the better tube, but only, if conditions are acceptable for DC/ current
the saratov should be the same, bcc. the russians transferred technology to chinese, and construction is the same. I opened the 6P15 and took the ratios between grind number windings and distances from g1, g2 g3.
the max. given dissipation of G2 is given for 1.5W, ( 6P15). this may have a reason: first for lifetime, second for linearity. the grid wire diameters (6P15) are the same as for EL84 ( 2.5W for G2). normally, russian tubes can be overloaded to a certain degree.
The best operation, and most linear way for the 6P15 is below 200V for the G2
The 6P14 plate is rated for 14W
the 6P15 plate is rated for 12 W
but: both have the same plate dimension, i have measured.
There may be some relabeled for a reason. dont know. in europe, a failed EL84 were relabeled as EL82 with less rating.
as i am incontact with suppo, we will test an check these things , and inform the community about the results.
my general advice: stay with the 6P15 instead of EL84, bcc. its the better tube, but only, if conditions are acceptable for DC/ current
6p15
6P15 ( SV83 ) is a video tube, so they need to have a bandwidth of minimum of 5.5MHz depending on the TV system. Audio tubes don't need this big bandwith. therefore audio tubes need ( have ) less linenarity over the frequency.
but linearity isn't all. unlinearity is creating a certain sound, less sterile, depending on what kind of distortion or unlinearity.
6P15 ( SV83 ) is a video tube, so they need to have a bandwidth of minimum of 5.5MHz depending on the TV system. Audio tubes don't need this big bandwith. therefore audio tubes need ( have ) less linenarity over the frequency.
but linearity isn't all. unlinearity is creating a certain sound, less sterile, depending on what kind of distortion or unlinearity.
If you are in contact with Suppo, I would recommend you advise them that they need to improve the design of the transformers. The OPT I disected looks like 1930s safety quality.
http://www.diyaudio.com/forums/tubes-valves/157134-meng-yue-mini-schematic-28.html
They need to use modern design techniques with margin tape, better isolation tape between primary and secondary, vacuum impregnate / Varnish soak the assembly, etc.
This may not improve the sound, but it is a safety issue.
http://www.diyaudio.com/forums/tubes-valves/157134-meng-yue-mini-schematic-28.html
They need to use modern design techniques with margin tape, better isolation tape between primary and secondary, vacuum impregnate / Varnish soak the assembly, etc.
This may not improve the sound, but it is a safety issue.
here the grid ratios compared to el84:
Comparison between 6BQ5 and chinese 6P15, both are true penthodes.
6BQ5 G2 is rates 2W, 300V
6P15 is rated 1.5W, max 200V
the tubes were opened:
spacings between the electrodes were found about to be the same.
Tests were performed with a micrometer, dimensions in mm:
6BQ5 6P15
G2 turns ~27 G2 turns ~ 35
G2 wire dia: 0.06 G2 wire dia: 0.06
G2 turns spacing: ~ 0.98 G2 turns spacing: 0.75
G3 turns: 10 G3 tuns: 21
G3 wire dia.: 0.1 G3 wire dia: 0.1
G3 turns spacing: 2.5 G3 turns spacing: 1.1
Cathode emission coating length in both tubes is ~ 25.5mm
in the 6P15 the suppressor grid has a bigger influence than in the 6BQ5
Steve
maybe not nice to read in this form
Comparison between 6BQ5 and chinese 6P15, both are true penthodes.
6BQ5 G2 is rates 2W, 300V
6P15 is rated 1.5W, max 200V
the tubes were opened:
spacings between the electrodes were found about to be the same.
Tests were performed with a micrometer, dimensions in mm:
6BQ5 6P15
G2 turns ~27 G2 turns ~ 35
G2 wire dia: 0.06 G2 wire dia: 0.06
G2 turns spacing: ~ 0.98 G2 turns spacing: 0.75
G3 turns: 10 G3 tuns: 21
G3 wire dia.: 0.1 G3 wire dia: 0.1
G3 turns spacing: 2.5 G3 turns spacing: 1.1
Cathode emission coating length in both tubes is ~ 25.5mm
in the 6P15 the suppressor grid has a bigger influence than in the 6BQ5
Steve
maybe not nice to read in this form
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